Fractional separation of oil with a complexing agent



Sept 22, 1953 G. B. ARNOLD ETAL 2,653,122

FRACTIONAL SEPARATION OF OIL WITH A COMPLEXING AGENT SUCH As URBA 1N THE PRESENCE oF A soLvENT LIQUID Filed Dec. 22, 1948 K hu lll, lll i w QUQQ x SQ Smm N .WWHQW m Parenyedv'sept.. 22, 4195s UNlrl-:o srA'rs s? PAT' FRACTIGNAL SEPARATION F OIL all l COMPLEXING AGENT SUCH AS URE EN THE PRESENCE 0F,A SOLVENT LIQ George B. Arnold, Glenham, and Howard V. Hess and William E. Skelton, Beacon, and Walter V.

' (lverliangli,

Texaacompany, New York, N. Y.,

tion ci Delaware JFishkill, N. Y., assignors to The.

This invention relates to the treatment oi' oil such as hydrocarbon mixtures and the like to e'ect'separation therefrom of constituents which. under-suitable conditions in the presence of a complexing agent such as urea and a solvent liquid, form complexes which are separable from the mixture undergoing treatment.

The invention broadly contemplates subjecting the feed mixture to contact with a complexing agent such as urea in the presence of a solvent liquid such as a low molecular. weight aliphatic alcohol which is at least partially mlscible with the agent and which is essentially immiscible with the oil. Contact is edected in a series of contact stages, each comprising mixing and settling zones, forming in each stage solvent-rich and oil-rich liquid phases, respectively, the solvent-rich phase being relatively rich in complexed constituents as solid complex and the 011- rich phase being relatively lean in said constituents. These phases are separately Withdrawn from each settling zone, the oil-rich phase Withdrawn from a preceding stage being conducted to its succeeding stage. The oil-rich phase discharged from the final settling zone is removed and further treated to recover therefrom a desired oil product.

Solvent-rich phase removed from the nnal settling stage may be recycled to the initial contacting stage, while solvent-rich phase withdrawn from theinitial stage may be discharged for furthertreatment in order to remove the coma Solvent Liquid, an operation is disclosed involving employment of a continuous countercurrent ilcw contacting column. The method of the presthereof. It may be applied to the treatment of plexed constituents therefrom. The residual solvent and complexing agent from which the complexed constituents of the feed oil have been removed are recycled to the system.

' According to a preferred modification, the operation is carried out so as to form three phases or layers in each settling zone. In this type of operation, oil-rich layers vand solvent-rich layers, respectively, are obtained and in addition an interphase layer in which the solid complex is con' l f'lled December 9, 1948, now U. S. Patent No.

2,637,681, for Fractional Separation of Oil With an Organic Complexing Agent in the Presence of oils derived from animal` and vegetable sources for the purpose oi' separating oxygen-containing compounds therefrom.

The invention is particularly eilective for removing wax from relatively low boiling hydrocarbon oil' fractions for the production' of' refrigerator. oils characterized by having an extremely low pour point and freedom from wax cloud or haze in Freon 12 solution at temperatures as low as minus '10 F. Likewise, it is applicable to the dewaxing of gas oils for the production of diesel oil.y

It is contemplated that organic agents other than urea. may be employed and which-have the structure:

where X may be oxygen or sulfur. Thiourea and urea are examples. l

Suitable solvents are polar compounds and comprise alcohols, either aliphatic or cyclic, ketones, glycols, amines, esters, dioxane, aniline, etc. Aliphatic alcohols having from 1 to 5 or more carbon atoms per molecule and particularly normal and isopropyl alcohols 'are useful solvents. Either straight chain or branched chain alcohols may be employed; also alcohols diluted with water or with other modifying agents.

In lorder to describe the method of operation in more detail, reference will now be made to the flow diagram of the accompanying drawing, illustraiing a method of operation for the manu-` facture of a refrigerator oil, charging a lubricating oildistillate having a Saybolt Universal viscosity of 300 seconds at 1ct ll. containing about 1.0 per cent wax by volume and having a pour test of minus 25 F.

The charge oil is'obtained from a source not vshown and conducted through a pipe l to a mixer 2. Advantageously, a stream of solvent such as isopropyl alcohol at least saturated with a complexing agent, such as urea. is conducted through pipe 3 from a source referred to later and injected into the feed oil stream flowing through pipe I to the mixer 2. If desired, how` ever. the solvent saturated with urea may beV isopropyl alcohol, the alcohol being saturated .with urea. The top layer collecting in the settler I is a solvent-rich layer comprising mainly isopropyl alcohol substantially saturated with urea, While the interphase layer relatively' small in proportion to the other two layers, consists essentially of solid complex betweenwax and urea associated'with some solvent and oil.

A stream of oil-rich liquid is drawn oif from the 4bottom of the settler through pipe Ill and conducted to a mixer I I wherein it is mixed with the 4 stream of isopropyl alcohol containing urea in excess of that required to saturate the alcohol at the temperature prevailing in the contacting stages. From the mixer II the resulting mixture ilows through -pipe I! to a settler I3, likewise maintained at a temperature of about 100 F.

Operations in this settler are similar to those in settler 1 so that the formation of three layers occurs. The oil-rich phase formed in settler I3 is continuously drawn of! through pipe I5 and discharged for further treatment, as will be described later.

The interphase liquids collecting in both set-- tlers 'I and I3 are drawn off through pipes III and II, respectively, which pipes lead to a common pipe 22 by which the interphase liquid is conducted to a filter 23. v

By means of the lter 2l, the complex material, which is in crystalline or solid form, is filtered out of the associated oil and alcohol. The complex in the form of illter cake is discharged through conduit 24 for further treatment, as will be described.

The filter may be a conventional rotary drum vacuum filter having provision for washing of the iilter cake in situ with additional alcohol or, for that matter, with some other suitable wash solvent, such as benzene, to permit obtaining a washed filter cake of Icomplexes which is substantially free from adhering oil. i

Instead of filtration, it is contemplated that other separating means may be utilized, such as centrifuging or thickening in 4a conventional thickener.

The filtrate is drawn ou through pipe 25 and can be conducted through a vessel 30 containing urea in solid particle or lump form. The filtrate stream ilows through the vessel I0 in direct contact with solid urea, effecting some solution there-y of. The extent of solution is regulated by the temperature 'maintained Thus. the illtrate stream owing through pipe 25 can be heated to any desired extent in a heat exchanger 29. For example, it may be heated to a temperature of about 125 F.

While the single vessel 3l is shown it will be understood that two or more such vessels may be arranged in parallel so that one vessel may be charged, while the other is on stream,

The emuent stream urea at about F. is conducted through a pipe 3|. branch pipe I2 leading to the mixerl I I. Another portion may be diverted through pipe I3 leading to the mixer 2.

The solvent-rich liquids accumulating in the settlers 'I and Il are drawn olf through pipes Il and 4I, respectively. Pipe .40 communicates with pipe Il, previously referred to, while pipe 4I may connect with a branch pipe 42 and also with pipe 2B. In this way, the solvent-rich streams from both settlln zones may be conducted through the saturating vessel 30 and thereafter returned to the contacting zones. l

.Referring now to the oil phase liquid dis'- charged through pipe I5 from settler I3: this stream is conducted ,to an extractor I0 wherein it is subjected to countercurrent washing with a stream of methyl alcohol introduced to the lower portion of the extractor 50 through pipe 6 I. 'I'his washing can be eil'ected at a temperature of about 100 F. and etlfects removal of residual urea retained inthe oil and isopropyl alcohol ilowing into the extractor from pipe I5, since urea is substantially more soluble in methyl alcohol than in isopropyl alcohol.

The washed oil and isopropyl alcohol are discharged through pipe 52 into a stripper I3 wherein the isopropyl alcohol yand any residual methyl alcohol are distilled from the oil as a distillate.

The solvent-,free'oil is discharged through pipe ll, while the aforesaid distillate is discharged through pipe 5l. condenser 56 and pipe 51, con- :iecting with a pipe 58` leading to a fractionator In the fractionator 69 the methyl alcohol is distilled i'rom the isopropyl alcohol, the distillate being removed through pipe 60, condenser 6I and pipe 62. Part of the resulting condensate in pipe 6I provides the wash solvent flowing through pipe II to the extractor 50. The isopropyl alcohol which may still retain a small amount of urea is discharged from the fractionator through pipe 63 for return to the contacting system at any point desired. Thus, it may be used as solvent make-up entering the system through the pipe IA.

Another portion, ofthe methyl alcohol condensate from pipe B2 may be conducted through pipe 62A and injected into the .lter cake discharged through pipe ZI. This mixture flows through pipe 1.0 and a heater 1I wherein it may be heated to a temperature of about F. From the heater 'II it flows through pipe l2 to a separator 13 wherein stratiication occurs forming Aa methyl alcohol layer containing urea broken .from the wax and a wax layer substantially free from alcohol and urea.

The wax is dischargedthrough pipe 1I, while the alcohol and urea solution is drawn oir through pipe IB which communicates with the previously vmentioned pipe 58 leading to the fractionator 59.

. 'Ihe wash solution of methyl alcohol containing urea removed from the oil in the extractor 50 is conducted through a pipe Il also communicating with the pipe BI'.

According to a modified type of operation, coni ditions may be adjusted so that only two phases are withdrawn from the settlers of each contacting stage, namely.` an oil-rich layer and a solvent- 'rich layer containing the complexed material.

In this case, the pipes 20 and 2| are blocked oil and the solvent-rich layers containing the complexed material are drawn oi through pipes 40 and 4 I, and each stream may be conducted in toto of .solvent saturated with.

This stream may be diverted in part through v through the by passes indicated by the broken `rich phase remo ed from the settler lll may be conducted-to the ucceeding mixer H, while the solvent-rich layer from the settler it'may be recycled to the mixer 2.` Thus the solvent-rich liquid from settler 1 flows through p'ipe 40, heater 29, saturatingVY vessel 3i) and pipe 32 to the mixer Il. Solv/ent-rich liquid from settler I3 ilowsthrough pipe Il, heat exchanger 43, pipe 4t to a saturating vessel 45, similar to the vessel 30 already referred to. From the vessel 45, the liquid flows through pipe 46 into pipe 3 to the mixer 2. In this latter type of operation the solvent-rich phases drawn oil through pipes 40 and 4l may or may not contain the bulk of the complexed materiallelsewhere described as being removed as interphase material.

By way of example and when operating so as to remove three separate phases or layers from each settling stage, the 300 viscosity feed oil is charged to the mixer 2 at the rate of 350 barrels per day. In this mixer it is mixed with about 3 volumes of alcohol-rich liquid per volume of feed oil, the alcohol-rich liquid comprising about 68.9% isopropyl alcohol, 27,4% oil and 3.7% urea. introduced from the pipe 3.

'I'he interphase liquid removed through pipe 20 from the settler 1 amounts to about 0.5 volume per volume of -feed oil.

pipe 2i. The volume of oil-rich phase removed from settler l through pipe i3 amounts to about 1.4 volumes per volume of feed oil, and it is mixed in the mixer il with about 2 volumes of solventrich liquid, similar in composition to that used for mixing with the fresh feed oil in mixer 2.

The oil-rich liquid discharged from settler i3l through pipe I5 amounts to about 450 barrels, of which about 346 barrels are wax-free oil having a pour test of 25 F. and a Freon Cloud of about -65 to 75 F., as compared with above -22 F. for the feed oil.

The interphase material is drawn off through pipes 20 and 2| to the lter 23 and is ltered to produce about 20 barrels of complex and a filtrate amounting to about 1.14 volumes per volume of feed oil, this ltrate consisting of approximately 68% alcohol, 27.5% oil and 3.6%` urea.

The aforesaid Freon Cloud is determined by mixing the oil with Freon l2 in the proportion of about 90% Freon and 10% oil, chilling the mixture, and observing the point at which wax haze appears.

The oil discharged from the stripper 53 through pipe 5I may be subjected to washing with water and then dried by passage through a conventional drieror blotter press to produce a finished refrigerator oil.

In the event of there being a substantial amount o'f oil retained in the interphase or complexed material, it may be subjected to washing or repulping with a suitable oil solvent, such as benzene or other benzenoid hydrocarbons. repulped mixture can be subjected to settling, centrifuging or filtration, etc. to obtain an oil- A similar quantity of this. Amaterial is withdrawn from settler i3 through The free complex which can then be decomposed to or by the addition of water with or without heating. v

The oil-rich liquid drawn off from thebottom of the settling zones can be subjected to distillation to remove retained solvent and amide from the dewaxed oil. l y

While reference to the treatment of a refrigerator type of lubricating oilhas been specifically described, nevertheless the process has application to the treatment of other types of lubricating oil, including' wax distillates and residual cylinder stocks. If desired, these relatively more viscous feed oils may be diluted with aromatic hydrocarbons, such as benzene, toluene, xylene or mixtures thereof, prior to introduction to the mixer 2 in order to facilitate effective contact between the feed oil and the urea-saturated alcohol. The diluent may be a petroleum naphtha or naphtha hydrocarbon mixture or a low boiling hydrocarbon having from 3 to 5 or more carbon atoms per molecule.

The use of the diluent is advantageous in the event that it is desired to subject either the solvent-rich phase or the oil-rich phase removed from the settler i3 to a subsecuent filtration..

The oil-rich phase `may under certain conditions retain a substantial amount of complex or crystallized material, and dilution with a low molecularweight hydrocarbon solvent may be advantageous in order to eifect removal of the crystalline material by filtration.

Likewise, it maybe desirable to-subiect the complex removed from the settlers to filtering in which case the complex may be diluted with a low molecular weight hydrocarbon or an aromatic hydrocarbon, such as benzene, to dissolve the small amount of retained oil and facilitate its removal by filtration.

vThe process of this invention may .be applied to the removal of residual wax from a` Waxbearing oil that has previously been subjected to dewaxing by conventional filtration or centrifuging in the presence of a diluent or solvent at low temperature and thus effect a further reduction in the pourpoint of the oil. On the other hand, the 'process of this invention maybe used to effect a preliminary removal of wax prior to conventional dewaxing. The wax-oil feed in the process of this invention may be a mixture of relatively wide boiling range or may be a mixture of relatively narrow boiling range, such as the individual fractions obtained by fractional distillation of a wax distillate.

Simultaneous removal of wax and resinous or asphaltic material may be effected by suitable selection of solvents or diluent liquids. For example, a high molecular weight aliphatic'alcohol, such as amyl, may be employed where it is desired to effect precipitation of resinous and asphaltic constituents from the oil. such precipimed constituents being removed along with the complexed material.

Although separation of waxy hydrocarbons from hydrocarbon mixtures has been mentioned specifically, it is contemplated that other constituents capable of complexing with the urea or other agent may be removed. Normal olefins and also aromatic and naphthenic compounds having long aliphatic side chains enter into complex formation with urea and thus can be sep- 7 Y arated in this way from hydrocarbon mixtures containing them. It is contemplated that certain derivatives oi' urea, such as the substituted ureas, may be employed, for example, ethanol urea. di- Aethyl urea, and butyl urea. Y

. Mention has been made oi' decomposing the complex wax cake with methyl alcohol, but ii desired, hot isopropyl alcohol may be used. For example, the oil-rich phase discharged from the process may be subjected to distillation to strip residual solvent and amide-therefrom and this hot distillate may be used for decomposing the associated complex cake.

, Obviously many modications and variations of the invention, as hereinbeiore set forth, may

be made without departing from the spirit and scopethereoi, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim: 1. A continuous method of treating hydrocarbon oil containing constituents which form crystalline complexes with anorganic compound hav ing the structure: f

where 'X is selected from the group consisting of oxygen and sulfur, and wherein the oil is subjected to contact with said compound in the presence of C3 aliphatic alcohol in a series o! treating stages each comprising mixing and settling zones, the method comprising forming a ilrst mixture oi' said oil with recycle solvent liquid and oil, as later deiined, said recycle solvent and oil containing said complexing compound.

8 mineral oil by subjecting said oil to contact with an organic compound having the structure' e ./NHs I where X is selected from the groupconsistins o! oxygen and sulfur, and wherein the oilis subjected to contact with said compound in the presence of C: aliphatic alcohol in a series of treating stages each comprising 4mixing and settling zones, the method comprisingtorming a iirst mixture o! said mineral oil with recycle solvent liquid and oil, as later denned. said recycle solvent and oil containing said complexing compound, the volume oi alcohol in said resulting iirst mixture being large relative tothe volumeof reed oil, subjecting the resulting mixture to settling -in a settling zone at a temperature in the range of about 'I0 to 150 'F., 'forming in said settling zone a solvent-rich liquid layer, an

. oil-rich liquid layer and an inter-phase layer rich in complexed wax` constituents, separately withdrawing a stream of each layer, conducting withdrawn oil-rich liquid to a succeeding stage, forming with said withdrawn oil-rich liquid a second mixture with a further quantity of said recycle'solvent and oil containing complexing compound, the volume of alcohol in the resulting second mixture being large relative to the volume of oil therein, subjecting this second mixture "to settling in a second settling zone at a temperature in the range of vabout 'I0 to 150 F.,

the volume of alcohol contained in said resulting mixture being large relative to the volume of feed oil, subjecting the resulting mixture'to settling in a settling zone at a temperature in the range of about 70 to 150 F., forming in said settling zone a solvent-rich liquid layer, an oilrich liquid layer and an inter-phase layer rich in complexed constituents, separately withdraw- .ing a. stream of each layer, conducting withdrawn oil-rich liquid to a succeeding stage, forming with said withdrawn oil-rich liquid a second mixture with a further quantity of said recycle solvent and oil containing complexing compound the volume of alcohol in the resulting second mixture being large relative to they volume o! oil therein, subjecting this second mixture to settling in a second settling zone at a temperature in the range of about 'I0 to 150 F., forming in the second settling zone a solvent-rich liquid layer, an oil-rich liquid layer and an inter-phase layer rich in complexed constituents. seperately withdrawing a stream of each layer. discharging oil-rich liquid withdrawn from said last menforming in the lsecond settling zone a solventi rich liquid layer, an oil-rich liquid layer and an inter-phase layer rich in complexed wax constituents. separately withdrawing a stream of each layer, discharging oil-rich liquid withdrawn from saidy last mentioned settling zone, commingling inter-phase layers withdrawn from both settling zones, filtering the complexed wax constituents from the commingled -mixture to form a recycle oil-rich stream substantially free from complex, -commingling solvent-rich streams withdrawn from said settling zones -with said complex-free recycle oil stream, incorporating complexing compound in the resulting recycle stream mixture to form the aforesaid recycle solvent liquid and oil, and supplying make-up alcohol to the initial mixing zone to maintain the alcohol requirement for the system.

3. A continuous method of separating wax from mineral oil by subjecting said oil to contact with an organic )compound having the structure: v A

/NHQ x=o\ where lx is `selected from .the group consisting oi' oxygen and sulfur, and wherein the oil is subjected to contact with said compound in the presence of an aliphatic alcohol having from 1 to 5 carbon atoms per molecule in a series of treating'stages each comprising mixing and settling zones, the method comprising forming a first mixture of said mineral oil with recycle solvent liquid and oil. as later defined, said recycle solvent and oil containing said complexing compound, the volume of alcohol contained in said resulting first mixture being large relative to the volume of said oil, subjecting the resulting mixture to settling in a settling zone at a temperature in the range of about F., forming inl said settling zone a solvent-rich liquid layer,

an oil-rich liquid layer and an inter-phase layer rich in complexed wax constituents, separately withdrawing a, stream of each layer, conducting withdrawn oil-rich liquid to a succeeding stage, forming with said withdrawn oil-rich liquid a second mixture with a further quantity of said recycle solvent and oil containing complexing compound, the volume of alcohol in the-result ing second mixture being large relative to the volume of oil therein, subjecting this second mixture to settling in a second settling zone at a temperature in the range of about 100 F., forming in the second settling zone a solvent-rich liquid layer, an oil-rich liquid layer and an interphase layer rich in complexed wax constituents, separately withdrawing a stream of each layer, discharging oil-rich liquid withdrawn from said last mentioned settling zone, commingling interphase layers withdrawn from both settling zones, filtering the complexed constituents from the commingled mixture to form a recyclel oil-rich stream substantially free from complex, commingling solvent-rich streams withdrawn from said settling zones with said complex-free recycle oil stream, incorporating complexing compound in the resulting recycle stream mixture References cited m the me of this patentr UNITED STATES PATENTS Number Name Date 2,151,529 Roberts i. Mar. 21, 1939 2,234,916 Jones Mar. 11, 1941 2,301,965 Mauro et al. Nov. 17, 1942 2,499,820 letterly Mar. '7, 1950 2,520,715 Fetterly Aug. 29, 1950 OTHER REFERENCES U. S. Technical Mission, Reel 143, translation by Shell Development Company, of German application B 190,197 (Bengen), May 22, 1946 (5 pages, pages 2-6 inclusive only) (included in Index released May 31, 1946). 

1. A CONTINUOUS METHOD OF TREATING HYDROCARBON OIL CONTAINING CONSTITUENTS WHICH FORM CRYSTALLINE COMPLEXES WITH AN ORGANIC COMPOUND HAVING THE STRUCTURE: 